Effect of High vs Low Doses of Chloroquine Diphosphate as Adjunctive Therapy for Patients Hospitalized With Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection

An interim analysis of this small randomised comparison of two chloroquine doses found the higher dose (600mg BD 10 days) was associated with more toxic effects (particularly QT interval prolongation) and lethality, and its use for severe Covid-19 should not be recommended.

SPS commentary:

The authors note that they were not able to independently assess the toxicity of chloroquine because all patients were already using azithromycin, as per hospital protocol, and most were also receiving oseltamivir for suspected influenza infection, which also increases QTc interval and could have adverse cardiac effects.  Based on their preliminary findings however they conclude the higher chloroquine dose should not be recommended for critically ill patients with COVID-19, especially when taken concurrently with azithromycin and oseltamivir.


The study had no placebo group, as chloroquine was being used routinely in Brazil in patients with Covid-19. This and the limited sample size meant an assessment of the efficacy of chloroquine was not possible.


JAMA Network Open